Draw Angle
Moderator: Shoshanah Marohn
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Draw Angle
Looking at the underside of my MSA Classic, I notice that some of the rod levers are canted towards the changer, some are at a rt. angle and some are canted away from the changer. I do not know the proper name for these short levers but they have several holes that holds a small roller that tightens onto the aluminum pull rod with a grub screw. I think the proper or ideal position for this lever should be just past the rt. angle position so the total swing of the lever is split evenly with 1/2 either side of the rt. angle position. Is this true? In setting up the guitar, should I be changing the angle of these levers to this position?
Thanks in advance for your comments.
Alvin
Thanks in advance for your comments.
Alvin
The differing angles help time the pulls to start and end at the same time. The 'acting' radius on the crank is changed by the different angles giving you virtual infinesimal refinement of the pulls. What you see could be the hack work of an amateur, or the master work of an experienced technician...you'll have to gauge it by how the guitar plays and the pulls work together.
- Riley Hart
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- Mike Wheeler
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IMHO, what you are seeing with the angles of the bellcranks is an adjustment that makes the pedal, or lever, stopping point "feel" solid without having to press hard to keep it there. It's all about leverages.
If you don't know how to set these leverages, you'd best get a good steel mechanic to take a look at it for you. There's more involved in setting one up than just the hole positions the rods are in.
Some people hate these round cross-shafts in the older MSAs, but the pedals and levers can be set up to feel incredibly fast and accurate when done right.
If you don't know how to set these leverages, you'd best get a good steel mechanic to take a look at it for you. There's more involved in setting one up than just the hole positions the rods are in.
Some people hate these round cross-shafts in the older MSAs, but the pedals and levers can be set up to feel incredibly fast and accurate when done right.
Best regards,
Mike
Mike
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Alvin -
You are entirely correct. Tom Gorr has added a useful bit of information.
Ideally, any pull should be "linear", that is, in the same direction as the rod. However, everything in a PSG is rotational - a circular motion. In order to reduce the effort required to pull a changer finger, the most "linear" configuration is to be found where the direction of the pull is tangential to the arc formed by the radius of the rotating bellcrank, + and - about the center point of the arc. Some may quibble about how much energy is saved by adhering to this fact but the reasoning is sound, nonetheless. The same reasoning should be applied to the connection between the pedal rod and the actuating lever attached to the crossrod.
Richard
You are entirely correct. Tom Gorr has added a useful bit of information.
Ideally, any pull should be "linear", that is, in the same direction as the rod. However, everything in a PSG is rotational - a circular motion. In order to reduce the effort required to pull a changer finger, the most "linear" configuration is to be found where the direction of the pull is tangential to the arc formed by the radius of the rotating bellcrank, + and - about the center point of the arc. Some may quibble about how much energy is saved by adhering to this fact but the reasoning is sound, nonetheless. The same reasoning should be applied to the connection between the pedal rod and the actuating lever attached to the crossrod.
Richard
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Thanks All. Yes, after looking at the underside photos of guitars on this forum, it appears as though the bell cranks are adjusted so they are at a right angle to the pull direction. Mine are all over the place so I think I will try to make some adjustments. I have learned about the ergonomics of the pedals and levers. Adjusting the relative height of the pedals and position of the levers so as to make it natural to push the A pedal while operating the LL lever (for example) has taken a while but I'm getting there. Thanks to everyone who commented. Your help is invaluable.
Alvin
Alvin
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- Larry Bell
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My first 4 guitars were MSA Classics. The bellcranks only had 4 positions to adjust the leverage (i.e., stiffness and amount of travel/pull) AND the TIMING. Some other guitars have 14 or more positions on the bellcrank, allowing very precise timing (when a pull starts). The MSA Classic design had round cross-shafts which would allow setting, e.g., a full step raise on the 5th and 10th strings so that each started at the same time and pulled to the stop, by moving the bellcrank a bit shy of or a bit past perpendicular. I WHOLEHEARTEDLY agree with the advice NOT TO MESS WITH THE SETUP until you completely understand what you're doing and how to un-do it.
Just my take on it.
Oh, and I'll add, BE SURE TO TIGHTEN THE BELLCRANKS VERY FIRMLY, especially if they are not perpendicular. They can slip if not really firmly tightened. Just a word to the wise. I've had 'em slip on gigs and it sometimes takes a minute to figure out that's what the problem is.
Just my take on it.
Oh, and I'll add, BE SURE TO TIGHTEN THE BELLCRANKS VERY FIRMLY, especially if they are not perpendicular. They can slip if not really firmly tightened. Just a word to the wise. I've had 'em slip on gigs and it sometimes takes a minute to figure out that's what the problem is.
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My CD's: 'I've Got Friends in COLD Places' - 'Pedal Steel Guitar'
2021 Rittenberry S/D-12 8x7, 1976 Emmons S/D-12 7x6, 1969 Emmons S/D-12 6x6, 1971 Dobro, Quilter ToneBlock 202 TT-12
Larry, by having the round cross shafts, the MSA has much more flexibility than even the 14 hole Emmons cranks. If it's near TDC, it pulls its fastest, but when they lean over, they're pulling slower.
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Lane is right. When the bell crank is tilted away from the perpendicular, the arc through which it moves is a motion of combined (or resultant) force consisting of both horizontal and vertical motion (vectors).Lane Gray wrote:Larry, by having the round cross shafts, the MSA has much more flexibility than even the 14 hole Emmons cranks. If it's near TDC, it pulls its fastest, but when they lean over, they're pulling slower.
With the bell-crank set just behind TDC, there is less vertical (wasted motion) and more horizontal (pulling) motion acting at the changer.
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Georg -
I think that I've gotta correct your assessment.
When the bellcrank is leaning towards the changer, the horizontal component of the motion is greater than the vertical moment. As it is rotated further, the moment is almost vertical, resulting in little movement from the changer. Hence, the movement of the changer is faster at the beginning.
I think that I've gotta correct your assessment.
When the bellcrank is leaning towards the changer, the horizontal component of the motion is greater than the vertical moment. As it is rotated further, the moment is almost vertical, resulting in little movement from the changer. Hence, the movement of the changer is faster at the beginning.
Tony, I think instead of calling it "wasted" motion, it might be better to call it "bled off," since you do it to pulls you WANT to slow down. "Wasted" carries a negative connotation, but you WANT unequal outcomes from an equal input.
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Lane, no negative connotation was implied. I meant, “wasted†as in motion that is not capable to do work (linear changer movement). From timing standpoint, that may desirable to get two changes to end simultaneously
Richard, Please feel free to correct me. To my understating of physics, movement at TDC is the closest you’re going to get to pure horizontal (or linear) movement at a bellcrank-pull rod couple traveling in an arc. The farther one moves away from that point, will result in greater vertical displacement (positive toward Top Dead Center or negative away from it). A tangent drawn across any point in the arc will show the resultant motion as compared to the horizontal cabinet floor. I'd tilt the bell cranks slightly aft, so the vertical motion is similar both at the start and finish of the pedal excursion.
Richard, Please feel free to correct me. To my understating of physics, movement at TDC is the closest you’re going to get to pure horizontal (or linear) movement at a bellcrank-pull rod couple traveling in an arc. The farther one moves away from that point, will result in greater vertical displacement (positive toward Top Dead Center or negative away from it). A tangent drawn across any point in the arc will show the resultant motion as compared to the horizontal cabinet floor. I'd tilt the bell cranks slightly aft, so the vertical motion is similar both at the start and finish of the pedal excursion.
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Another 'angle' (pardon the pun) on all this is that with the cranks mounted
on round cross-shafts, you can opt to cant the crank towards the changer
(at idle) and as the pull progresses, the force necessary to 'mash' the pedal
thru its range will increase, whereas, if conversely you opt to cant the crank
away from the changer, the force required to 'mash' the pedal thru its range
will decrease.
Of course, the 'rate of leverage' changes accordingly in each case,
but this option is one that can be taken into consideration.
~Rw
on round cross-shafts, you can opt to cant the crank towards the changer
(at idle) and as the pull progresses, the force necessary to 'mash' the pedal
thru its range will increase, whereas, if conversely you opt to cant the crank
away from the changer, the force required to 'mash' the pedal thru its range
will decrease.
Of course, the 'rate of leverage' changes accordingly in each case,
but this option is one that can be taken into consideration.
~Rw
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